Top Height Growth Research Articles

Study of dynamics of the cumulonimbus anvil of large vertical extent

Results are presented of analysis of development of a cumulonimbus cloud anvil with the top height exceeding 18 km, as observed in Central India. The anvil development is studied using the measurements from Meteosat-5 and with the WR-100 radar. Minimum air temperature measured from the satellite at the cloud top level is −105°C. The rate of cloud top height growth is, on average, 0.5 m/s. Horizontal extent of the anvil in the steering flow direction reached 85 km, and rate of the anvil propagation in horizontal direction was equal to 32.4 km/h. The anvil area, after the satellite data, reached 3675 km2. After the radar data, horizontal extent of the anvil reached 50 km, maximum area being 600 km2. Analysis of discrepancies between the satellite and radar measurements of the anvil area shows that a significant part of the anvil cannot be detected by the WR-100 radar because its potential is not enough high; the satellite measurement data improve significantly quality of information on the Cb characteristics.

Assessing the impacts of species composition, top height and density on individual tree height prediction of quaking aspen in boreal mixedwoods

In this study we developed an individual tree height prediction model for quaking aspen ( Populus tremuloides Michx.) grown in boreal mixedwood forests in Alberta using the nonlinear mixed model (NLMM) approach. We examined the impacts of density, species composition, and top height on aspen height predictions. Statistically significant stand level variables were incorporated into the base height–diameter model to increase the predictive ability and accuracy of the model at both the population and subject-specific levels. Our analyses showed that top height and density impacted height growth, but species composition did not. More importantly, we found that the inclusion of additional variables into the base model, despite improving model fitting statistics on the modelling data, did not improve the model's predictive ability and accuracy when cross-validated and when tested on an independent testing data set. Under the NLMM framework the base model performed as well as or better than the expanded models that contained other stand level variables. This has important theoretical and practical implications because, other than for biological reasons, more accurate local tree height predictions for aspen can be achieved simply by using the base height–diameter model fitted with the NLMM approach without the inclusion of other variables.

Modeling top height growth of red alder plantations

Height growth equations for dominant trees are needed for growth and yield projections, to determine appropriate silvicultural regimes, and to estimate site index. Red alder [ Alnus rubra Bong.] is a fast-growing hardwood species that is widely planted in the Pacific Northwest, USA. However, red alder dominant height growth equations used currently have been determined using stem analysis trees from natural stands rather than repeated measurements of stand-level top height from plantations, which may cause them to be biased. A regional dataset of red alder plantations was complied and used to construct a dynamic base-age invariant top height growth equation. Ten anamorphic and polymorphic Generalized Algebraic Difference Approach (GADA) forms were fit using the forward difference approach. The Chapman–Richards anamorphic and Schumacher anamorphic model forms were the only ones with statistically significant parameters that yielded biologically reasonable predictions across a full range of the available data. The Schumacher model form performed better on three independent datasets and, therefore, was selected as the final model. The resulting top height growth equations differed appreciably from tree-level dominant height growth equations developed using data from natural stands, particularly at the younger ages and on lower site indices. Both the rate and shape parameters of the Schumacher function were not influenced by initial planting density. However, this analysis indicates that the asymptote, which is related to site index, may be reduced for plantations with initial planting density below 500 trees ha −1. The final equation can be used for predictions of top height (and thus) site index for red alder plantations across a range of different growing conditions.

Estimation of height growth patterns and site index curves for Pinus radiata plantations in New South Wales, Australia

The objective of this study was to estimate the mean top height growth patterns and site index curves (base index age 20 years) for Pinus radiata stands grown in New South Wales, Australia. Garcia's stochastic differential equation version of the Bertalanffy-Richards equation was selected for stand height prediction using data from permanent growth and long-term experimental plots. This technique uses simultaneous maximum likelihood methods to estimate the global and local model parameters. Three regional base age invariant site index curves were created based on this height estimation methodology. These models may be used for modelling stand height growth as a component of a stand growth model and can also provide an indication of the productivity of the site quality of Pinus radiata stands planted in New South Wales, Australia.

Growth and Yield of Hybrid Larch (Larix×eurolepis A. Henry) in Southern Sweden

The interest in growing hybrid larch (Larix×eurolepis A. Henry) in Sweden has increased during the past few decades. This is mainly due to expectations concerning rapid growth, resistance to butt rot and durability of the wood. A yield study in hybrid larch was conducted based on 28 plots in southern Sweden. The plots were established on fertile sites in stands managed in practical forestry. A growth model was developed, including regression functions for basal area increment, stand form-height development and initial basal area. Top height growth curves from a Norwegian study were also included in the model. A yield table was calculated for the age span 15–45 yrs. The calculations showed that the yield of hybrid larch in southern Sweden compared with Norway spruce was slightly higher and especially more rapid when young. On fertile sites the mean annual volume growth peaked at an age of 35 yrs, at a level of 13 m3 ha−1.

Growth of Young Douglas-Fir Plantations Across a Gradient in Swiss Needle Cast Severity

Abstract During the past decade, Swiss needle cast (SNC) damage has intensified in many Douglas-fir plantations in the Coast Range of Oregon, particularly along the immediate north coast. In plantations with severe symptoms, growth losses and reduced tree vigor are evident, but the magnitude of growth losses associated with varying intensities of damage is not known. A growth impact study was conducted in 1997 to quantify retrospectively the relationship between growth losses and visual symptoms in 10- to 30-yr-old Douglas-fir plantations in coastal northwestern Oregon, a population totaling 75,700 ha. A random sample of 70 Douglas-fir plantations was selected from the population and evaluated for Swiss needle cast severity. One 0.02 ha plot was destructively sampled in each plantation to reconstruct past height and basal area growth trends and to characterize foliage loss and distribution. The SNC “effect” was assessed by comparing growth of plantations with varying degrees of Swiss needle cast to growth of those that retained maximal amounts of foliage, after correcting for initial stand density, Douglas-fir growing stock, age, and site index. Of numerous possible SNC indices, mean needle retention (yr) explained the largest amount of variation in both basal area and top height growth. Prior to 1990, top height growth was similar across all plantations after correcting for site quality and plantation age; but, by 1992, top height growth losses appeared and were proportional to apparent foliage losses. In 1996, top height growth was reduced by up to 25% relative to plantations with little or no SNC. Basal area growth reductions began to appear around 1990, and in 1996 basal area growth of the most heavily damaged plantations was 35% less than the growth that would be expected in absence of SNC damage. The inferred volume growth loss for 1996 averaged 23% for the 75,700 ha target population, but this loss averaged as high as 52% for the most severely impacted plantations. West. J. Appl. For. 17(2):86ߝ95.

Dynamics of a broadleaved ( Castanea sativa) conifer ( Pseudotsuga menziesii) mixed stands in Northern Portugal

In nature, forest ecosystems are composed by mixtures of species located in the understorey, intermediate and overstorey layers and a potential increase in productivity with mixed stands and plantations, compared to pure stands of the component species is widely accepted, although this has not generally been incorporated into forestry practice. In this experimental planting study, the types of mixtures tested includes three row mixtures with species changing in the planting line, two line mixtures with species changing between the planting line and two monocultures. The species growth pattern was analysed and productivity comparisons between mixed stands and pure stands of the component species were made using the relative yield (RY) and relative yield total (RYT) concepts. The species shows different top height growth patterns which are not influenced by the mixtures tested. Castanea sativa responds well to competitive pressure from Pseudotsuga menziesii which shows a higher productivity. In the row mixtures, the positive effect of interspecific competition yields to RYT values greater than 1.0. Mixture RYT values are steadily increasing with time and C. sativa monoculture has been the most attractive economic solution, although its importance compared with the most productive mixtures is diminishing over time. This species mixture represents a flexible silvicultural system, which will be in the future, a very important land use alternative in mountain areas.

Response of Eckespoint Lilo poinsettia to nitrite, substrate pH and etridiazole in a subirrigation system

Poinsettias (Euphorbia pulcherrima Willd. 'Eckespoint Lilo') were grown in pH-adjusted (4.5, 5.5 or 6.5) sphagnum peat substrates and subirrigated using a complete nutrient solution with three concentrations of nitrite (0, 1.75 and 3.5 mol m−3). The substrate also was either treated with a nitrification inhibitor (etridiazole) or remained untreated. There was a linear decrease in leaf and bract areas, top dry weight, plant height and root growth with increasing nitrite concentration. This response occurred at a rate of 10% mol−1 NO2− m−3 at a substrate pH of 4.5 or 5.5 and 6% mol−1 NO2 m−3 at a substrate pH of 6.5. Leaf and bract areas and top dry weight were greater at pH 4.5 than at pH 6.5. Etridiazole did not affect the response of plant growth to nitrite and (or) substrate pH. Key words: Aaterra, 5-ethoxy-3-trichloromethyl-1,2,4-thiadiazole, subirrigation, terrazole, truban

Modeling density-related Iodgepole pine height growth, using Czarnowski's stand dynamics theory

This paper presents a new density-dependent height-growth model for lodgepole pine (Pinuscontorta var. latifolia Engelm.) in Alberta. It predicts stand top height growth as a function of present top height, breast height age, and density. The model is an extension of Czarnowski's stand dynamics theory, using an iterative height increment model with variable site and density components. Using 946 annual growth periods from permanent sample plots, the calibration shows a good fit and simulates reasonable values, even beyond the database.

A Whole-Stand Growth and Yield Model for Interior Douglas-Fir

Abstract A whole-stand model, Simulation Of Stands (SOS), was developed for even-aged Douglas-fir (Pseudotsuga menziesii var. glauca) stands in the inland Northwest. The model consists of three new components: (1) volume prediction model, (2) basal area prediction model, and (3) survival model. Existing height growth models were used to estimate stand top height growth. The behavior and performance of SOS were evaluated by simulating stand development over time under alternative conditions and comparing the results with growth and yield concepts suggested in the literature. The predicted stand attributes from SOS were also compared with predictions from the Stand Prognosis Model and Stand Projection System (SPS). SOS behavior was similar to Prognosis for lower site indices, but more like SPS for higher site indices. The three models differed mainly with respect to stand top height growth and tree survival. West. J. Appl. For. 8(4):120-125.

Top height growth analysis on the three birch species

Top height growth analysis on the three birch species

Top Height Growth Curves for Sitka Spruce in Northern Ireland

An asymptotic relationship is fitted to top height-age measurements from a wide range of sites. A method of generating top height growth curves corresponding to different site indices is presented. By letting one parameter in the relationship be site specific it is shown how to obtain a system of either similar (anamorphic) or different (polymorphic) shaped curves. These may be used to allocate stands to site quality classes. The method may be applied to any data set consisting of pairs of top height-age measurements from different sites; the only proviso being that the curves obtained apply only within the age range of the data and to the site quality classes represented.